The effect of minimum wages on prices in Brazil

There is very little evidence on the effects of the minimum wage on prices in the international literature and none whatsoever for developing countries. This paper analyzes the effects of the minimum wage on prices using monthly Brazilian household and price data from 1982 to 2000 aggregated at a regional level. A number of conceptual and identification questions are discussed, for example: (1) Empirical evidence on price effects might help to answer the question of who pays for the higher costs: firms, consumers, or unemployed. The answer to this question is important for the controversial recent minimum wage debate. Employment might not be affected if firms are able to pass through to prices the higher labour costs associated to a minimum wage increase. (2) If the poor are the consumers of minimum wage labour intensive goods, or if these goods represent a large proportion of their consumption bundle, then minimum wage increases might hurt rather than aid the poor. Furthermore, if minimum wage increases are passed on to consumer prices causing inflation, they might again hurt the poor, who disproportionately suffer from inflation. This is particularly so in the presence of hyperinflation; even more so if the minimum wage has been used as anti-inflation policy in addition to its social role, as in Brazil. Robustness checks on the price effects at a regional level, on low and high income consumers and under low inflation are performed. Robust results indicate that minimum wage increases raise overall prices in Brazil. The resulting inflation is the same for the poor and the rich, smaller in low inflation periods, and larger in poorer regions

Black holes and fundamental physics

We give a review of classical, thermodynamic and quantum properties of black holes relevant to fundamental physics.Comment: Invited talk at the Fifth International Workshop on New Worlds in Astroparticle Physics, University of the Algarve, Faro, Portugal, January 8-10, 2005, published in the Proceedings of the Fifth International Workshop on New Worlds in Astroparticle Physics, World Scientific (2006), eds. Ana M. Mour\~ao et al., p. 71-9

Is the proton radius puzzle evidence of extra dimensions?

The proton charge radius inferred from muonic hydrogen spectroscopy is not compatible with the previous value given by CODATA-2010, which, on its turn, essentially relies on measurements of the electron-proton interaction. The proton's new size was extracted from the 2S-2P Lamb shift in the muonic hydrogen, which showed an energy excess of 0.3 meV in comparison to the theoretical prediction, evaluated with the CODATA radius. Higher-dimensional gravity is a candidate to explain this discrepancy, since the muon-proton gravitational interaction is stronger than the electron-proton interaction and, in the context of braneworld models, the gravitational potential can be hugely amplified in short distances when compared to the Newtonian potential. Motivated by these ideas, we study a muonic hydrogen confined in a thick brane. We show that the muon-proton gravitational interaction modified by extra dimensions can provide the additional separation of 0.3 meV between 2S and 2P states. In this scenario, the gravitational energy depends on the higher-dimensional Planck mass and indirectly on the brane thickness. Studying the behavior of the gravitational energy with respect to the brane thickness in a realistic range, we find constraints for the fundamental Planck mass that solve the proton radius puzzle and are consistent with previous experimental bounds.Comment: Updated with new dat

Collapsing shells of radiation in anti-de Sitter spacetimes and the hoop and cosmic censorship conjectures

Gravitational collapse of radiation in an anti-de Sitter background is studied. For the spherical case, the collapse proceeds in much the same way as in the Minkowski background, i.e., massless naked singularities may form for a highly inhomogeneous collapse, violating the cosmic censorship, but not the hoop conjecture. The toroidal, cylindrical and planar collapses can be treated together. In these cases no naked singularity ever forms, in accordance with the cosmic censorship. However, since the collapse proceeds to form toroidal, cylindrical or planar black holes, the hoop conjecture in an anti-de Sitter spacetime is violated.Comment: 4 pages, Revtex Journal: to appear in Physical Review